As the present time is called a card age, cash cards, credit cards, and various other cards have appeared on the market. Most of them are magnetic recording cards and especially cards of the business card size, which are convenient to carry, are very often used. However, since recording capacity is not so much assured in magnetic recording cards of such a size, it is at the present state that they are only used to the extent of memorization of collation card, e.g., secret code, account number or registration number, etc. extremely restricted. In this respect, optical cards which optically record information have the merit that the information content recorded is far greater than that of conventional magnetic recording cards.
Such a system to record information onto an optical card and then to reproduce information therefrom is disclosed in, e.g., the Japanese Patent Application Laid-Open No. 137245/86 publication. In this system, a direction of laser beam is controlled by two servo control mirrors, thus to carry out scanning of recording areas on the optical card. Further, a method is disclosed in the Japanese Patent Application Laid-Open No. 40325/84 publication to effect recording and reproducing while vibrating a laser beam in a direction vertical to the scanning direction of the optical card, and an actual mechanism for a scanning laser beam is disclosed in the Japanese Patent Application Laid-Open No. 214239/86. In addition, a format for recording data onto an optical card with high efficiency is disclosed in the Application No. JP86/00134 specification under the Patent Cooperation Treaty.
However, problems with the recording format of conventional optical cards are as follows:
(1) For an optical disc, it is sufficient to carry out scanning with a laser beam by revolving the disc. In contrast, since it is necessary for an optical card to be scanned by a laser beam lengthwise and breadthwise, a peculiar format suitable for an access to tracks is required.
(2) The recording area on the surface of an optical card is likely to be subjected to adhesion of dust or scratched, with the result that reading error may occur at the time of reproduction or playback.
(3) File management is required for an optical card. Namely, every time the content of a file is altered or modified, or a new file is added, it is necessary to update the directory. In the case of a magnetic card, it is easy to alter or modify data having been recorded once. In contrast, because data is recorded by formation of pits in an optical card of the DRAW type (Direct Read After Write type), it is impossible to eliminate or erase pits having been formed once at the present stage. For this reason, a file management system having a good efficiency suitable for an optical card is required.